The use of composite materials for decking is increasing. Composite boards are normally applied over a natural wood sub-frame of joists, and composite material fascia boards are often used as a decorative cover applied to the outer, vertical plane of the sub-frame joist structure, around the perimeter of the deck. Fascia boards have yielded long lasting and aesthetically appealing results, but have also created new installation considerations.
Composite decking and fascia materials experience a change in overall size when heated, referred to as thermal expansion. Natural wood framing members lose moisture content when heated and, as a consequence, shrink. This board expansion, combined with sub-frame shrinkage, results in directly opposing forces that cause problems all too frequently manifested as physical distortion of the composite fascia boards and/or broken screws. These problems are most commonly associated, throughout the industry, with the installation of generally thinner composite fascia board materials.
The combined expansion/contraction affects the fascia/joist combination both laterally along their combined length, as well as vertically in their combined height. Movement through expansion/contraction of the materials has been measured to be as much as ⅜″ loss in combined height. If screws are purchased in a heavy gauge so as to reduce breakage, the fascia material often distorts in an outward protrusion commonly referred to as “buckling” or oil-canning. This distortion takes place between the fixed screw locations, causing an undesirable appearance. If lighter gauge screws are used, the combined shear pressures of expansion and shrinkage between the materials can break the screw, losing installation integrity. The end-use customer in these instances often perceives the problem to be with the screws or with the fascia material and makes a manufacturer's warranty claim, when in reality, the biggest contributing factor is the natural wood components being used and a failure to allow for this natural movement during installation. Thus, there is a need to develop an installation method or system that allows for this expansion/contraction movement.
Accordingly, one object of the present invention is to provide new and improved drill bits and screws.
Another object of the invention is to provide new and improved drill bits and screws that allow for movement of fascia materials while reducing the shear pressure placed upon the screws, when fascia boards are fastened to wooden joists.